Minehunting With Radar And Rats

Frank Franklin II/AP
During a morning operation against the Taliban in Afghanistan's Helmand province in 2010, a British army contingent halted before a narrow pass reckoned to be mined with improvised explosive devices (IEDs). The day before, two of the unit's armoured vehicles had been destroyed nearby by IEDs (the crews were uninjured).

The commander, Lieutenant-Colonel Matt Bazeley, fired a rocket that pulled 200 metres of a fat, coiled hose out over the route ahead. Packed with about 1.5 tonnes of explosives, it detonated upon landing with such a force that the shock wave was felt at a command centre 13km (8 miles) away.

Python, as the mine-breaching system is called, is so powerful that before it is fired soldiers must ensure no civilians are within half a kilometre (on that morning, a B-2 bomber and a drone first scanned the area). Other methods used to detonate IEDs and landmines, such as armoured machines that flail the ground or sift through it like a potato harvester, are less violent. But setting off buried mines is not always the best option.

When conflicts cease and civilians return to resume their daily lives, mine-breaching alone cannot ensure that land is clear of the unexploded remnants of war. Scattered shrapnel and explosives residue make it difficult to confirm that no mines remain. Mines may survive blasts and some are designed to do so.

For example, the MAT/5 and Valmara 69, Italian anti-tank and anti-personnel mines, are detonated by the momentarily sustained pressure from a passing vehicle or foot. This means there is often no option but to resort to the laborious and dangerous process of clearing mines manually.

Humanitarian demining, as post-conflict mine clearance is known, is carried out by the army, non-governmental organisations (NGOs) and commercial companies. It usually involves deminers, dressed in moderately blast-resistant clothing (the heavy, full-body armour used by bomb squads is considered by many to be too restrictive), checking the ground with metal detectors and carefully prodding to find buried objects.

When the Anti-Personnel Mine Ban Convention, known as the Ottawa treaty, came into force on March 1st 1999, landmines were killing or maiming more than 9,000 people a year.

By 2012 casualties were down to some 3,620, roughly three quarters of them civilians, according to Landmine Monitor, the research arm of the International Campaign to Ban Landmines. Improved detection methods have helped, and there has been a big decrease in mines being planted--more than 130 countries are signatories to the Ottawa treaty (America is not, but follows its precepts). Even so, the Pentagon reckons that at least 45m landmines remain in the ground worldwide.

Deminers can struggle to find them with metal detectors because for decades most mines have been made largely from plastic. They might contain only one metal component: a firing pin smaller than a sewing needle, says Eddie Banks, a retired deminer and author of a book on landmine design.

But some hand-held detectors are sensitive enough to detect even a buried scrap of silvery paper from a cigarette pack, says Alex van Roy of the Armenian government's Centre for Humanitarian Demining and Expertise, a new body clearing mines in Armenia that remain after a war in the 1990s with Azerbaijan.

Such machines cost about $4,000 and some can be calibrated to take account of the soil's mineral content. This helps searching in soils rich in iron and aluminium, says Pehr Lodhammar, an equipment expert at the Geneva International Centre for Humanitarian Demining, an NGO. Nevertheless, progress can still be slow because everything detected must be treated as a potential mine until it is dug up, be it a splinter of shrapnel or a bottle cap.

Peering Below Ground

NATO forces in Afghanistan have been using a novel landmine detector known as AN/PSS-14. It combines metal detection with wideband ground-penetrating radar, which can reveal inconsistencies in the soil whether or not metal is present. The detector, developed by a clutch of American universities and L3 CyTerra, a Florida firm, uses algorithms to analyse data from each detection system to determine if buried metallic objects might be part of a mine.

GlobalSecurity.org, an American think-tank, reckons the AN/PSS-14 is a vast improvement over previous mine detectors and the Pentagon has promoted its use by demining organisations. But, as each machine costs more than $20,000, few have been purchased by NGOs because it is cheaper to employ people to clear mines manually.

In Lebanon a deminer's typical monthly wage is about $1,000; in Sri Lanka it is just $200. Moreover, the AN/PSS-14 requires a number of technical skills to operate which deminers with little formal education may not have, adds Mr Banks, the retired deminer.

For those with big budgets, even more elaborate detectors are being developed. Raytheon, an American defence firm, has developed a truck-mounted one that detects landmines and tunnels by sending acoustic and seismic signals into the ground. These signals cause minute vibrations which are measured with lasers.

The pattern of the vibrations can be used to predict what lies below. A smaller system which could be carried by a deminer might cost less than $100,000, reckons James Sabatier, a University of Mississippi engineer who is attempting to design one.

A detection system recently demonstrated by Gap EOD, an Australian firm, to a copper-mining company keen to avoid digging up unexploded bombs dropped in Laos by American warplanes in the 1960s and 1970s costs more than $250,000. This device, called UltraTEM, uses a 10kW generator to flood with electricity, 25 times a second, a thick copper cable laid on the ground in a loop about 100 metres in diameter.

This generates electromagnetic eddy currents in any buried metal and these currents can be detected on the surface with a hand-held receiver. UltraTEM is said to double the typical detection depth for a 250-pound bomb to more than five metres in certain soils.

Besides more sophisticated kit, it helps to have better intelligence on where IEDs and landmines have been planted in the first place. But obtaining reliable information is difficult, says Valeria Fabbroni, operations boss of the Swiss Foundation for Mine Action, an NGO known by its French acronym FSD.

This was the case in Sri Lanka after the defeat of the Tamil Tigers in 2009. An FSD team visited the insurgents' former fief in the north of the country to map areas thought to contain landmines but found that many locals were reluctant to speak, no doubt because some had supported the Tigers. The FSD team ended up studying the group's military doctrine and combing media reports for any mention of positions defended by the Tigers to help work out where landmines might be.

Now such surveys can get help from a free service offered by the European Space Agency. Its Space Assets for Demining Assistance project superimposes satellite photos of an area taken before, during and after armed conflict. By studying how the use of land has changed, a trained eye can spot a wealth of clues to the presence or absence of landmines. Previously productive farmland that has fallen fallow may well have been mined.

The same goes for areas where firewood is used for cooking or heating but fallen trees have not been collected. Buildings with unrepaired roofs, abandoned water wells and well-trodden new paths that appear circuitous also provide telltale signs.

An alternative system using photographs taken by aircraft is used by the Croatian Mine Action Centre (CROMAC), a government agency in Sisak, a town southwest of Zagreb. High-resolution colour images can reveal old defensive positions dug by militias. Fighting in the 1990s against ethnic-Serb forces left an astonishing 1.2% of the territory littered with landmines.

Those devices included the dreaded PROM-1, a "bounding" metal mine manufactured in the former Yugoslavia. The size of a litre bottle, it contains two charges. The first propels the mine a metre or so into the air; the second turns it into a shower of "high-velocity razors" that can kill a person 50 metres away, says Miljenko Vahtaric, CROMAC's head of international co-operation. Most of Croatia's landmine deaths have been caused by PROM-1s.

After a few months underground, almost all landmines leak vapours that betray the presence of explosives. The University of Connecticut has designed a fibrous film that can be laid on the ground like a carpet. It is treated with secret chemicals that change colour upon contact with vapour from plastic explosives. The film detects some explosives in concentrations as weak as a half dozen parts per trillion. Such sensitivity is impressive, but dogs can do much better.

Belgian, Dutch and German shepherds are used to help locate mines on the ground. (Beagles and spaniels have keen noses but their personalities are too flighty for minefield work.) Dogs, however, present a problem. They can be heavy enough to detonate an anti-personnel mine.

Sniffing Safely

A clever way around that comes from MECHEM, a subsidiary of Denel, a South African defence contractor. It uses a vacuum device to filter out particles from explosives that have seeped from the ground. The filters are sent to a laboratory where they are safely sniffed in controlled conditions by trained dogs. If the dogs detect explosives in a particular filter, the corresponding area of land, typically about 100 metres square, is demined.

Bees can also be trained to associate the whiff of explosives with food, but they can be hard to track. Rats, however, are more controllable. Dozens of giant pouched rats, tethered by deminers, are used to sniff out landmines in Mozambique. Teaching a rat to scratch the ground upon smelling explosives costs around EUR6,000 ($8,200), which is only a third of what it costs to train a dog, according to APOPO, a Belgian NGO that runs such a programme.

A rat can reliably check the ground faster than a human with a metal detector, says Zacarias Chambe, an APOPO deminer who uses rats in Mozambique's Tete province. Not one rat has made a mistake that has led to an accident, he adds. APOPO's rats have recently started work in Angola and are expected to begin this year in Cambodia.

Many of the new high-tech solutions are likely to remain beyond the financial reach of some civilian mine-clearing operations, at least until prices come down. Meanwhile, the job will continue to be done largely by hand with some improved kit and the assistance of well-trained animals.

Further into the future, a clever robot that is dexterous enough to unearth and carry away landmines may well be developed. But until then, one of the most dangerous jobs in the world is a long way from being automated.

A rat can reliably check the ground faster than a human with a metal detector